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Enzymes represent an attractive alternative to oxidative chemical breakers for several reasons. They are polymer specific, environmentally friendly, easy to handle, miscible, do not damage equipment and they are naturally regenerating catalytic breakers. Enzymes have been used with great success for many years as breakers in fracturing applications.However, traditional enzyme breakers derived from mesophilic sources have a tendency to unfold from their functional threedimensional conformation into an inactive form under high temperatures. Thermal unfolding of enzymes proceeds via a dynamic equilibrium between active and inactive states, which reduces the enzyme activity, prior to an irreversible unfolding step as the temperature increases.To maximize enzyme functionality, a new generation of polymer-specific, thermostable enzyme was developed.The gene coding for the new enzyme was obtained and codon optimized for production in a commercially available expression system. Additional genetic enhancements were made to increase the yield and stability of the enzyme and further lower production costs.

Increased interest in minimizing environmental risk from chemicals has sparked the innovation of new universal breakers for use in high-temperature fracturing fluids. Enzymes have been used for many years in fracturing applications with great success, but their use could be limited due to polymer specificity and thermal stability.A novel type of breaker system, derived from biological sources and displaying catalytic, polymer degrading activity similar to that of enzymes, was obtained and tested for its ability to reduce the viscosity and molecular weight of polymers used in hydraulic fracturing applications. The universal breakers (UB) are miscible, catalytic, renewable, biodegradable and are not polymer-specific. Additionally, these breakers do not display the thermal denaturation limitations of enzyme breakers, and can thus be used over a much wider temperature range.Three novel universal breakers were tested for their ability to break the viscosity of various oilfield polymers (guar, carboxymethyl guar, and xanthan) at temperatures of 175, 200, and 225 °F. UB-1 and UB-3 showed rapid catalytic activity at 175, 200, and 225 °F, and reduction in viscosity. UB-2 was more effective at temperatures equal to and greater than 200 °F. Additionally, all UB breakers showed activity against xanthan, with UB-1 and UB-3 being the most effective. This paper will describe the testing program for the viscosity-reducing ability of three novel universal breakers against both linear and crosslinked high-yield guar, guar, carboxymethyl guar, and xanthan in alkaline and high-temperature conditions. Comparisons of the UB breakers to conventional polymer-specific enzymes and oxidative breaker systems will be discussed. Finally, this paper will include recommendations for field applications, including economic impacts on fracturing fluid systems.

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